Let's break down the provided benchmark and explain what's being tested.

Benchmark Overview

The provided benchmark compares two approaches to filter an array in JavaScript: using a named function (fl) vs using an anonymous function (an arrow function with a single line).

Test Cases

There are two test cases:

1. fn named: This test case uses the named function fl(e) to filter the array ka. The function is defined as follows:

var fl = function(e) {
  return e !== k;
}

2. fn anon: This test case uses an anonymous arrow function to filter the same array ka. The function is defined as follows:

ka.filter(e => e !== k);

Library

In this benchmark, the filter() method of arrays is used in both test cases. The filter() method takes a callback function as its second argument and calls it for each element in the array.

Pros and Cons of Named Function vs Anonymous Function

Using a named function (fl) has some advantages:

• Readability: The code is more readable, as the purpose of the function is clearly stated.
• Debugging: It's easier to debug named functions, as they can be inspected in the debugger.

However, using named functions also has some disadvantages:

• Performance overhead: Named functions may incur a performance overhead due to the need for a lookup table (a cache of function calls) to find the correct implementation.
• Code size: The code will be larger due to the need to define and name the function explicitly.

Using anonymous arrow functions, on the other hand, has some advantages:

• Performance: Anonymous functions are typically faster, as they do not incur the overhead of a lookup table.
• Code size: Code is smaller and more concise.

However, using anonymous functions also has some disadvantages:

• Readability: The code may be less readable for those who are not familiar with arrow functions.
• Debugging: It can be harder to debug anonymous functions, as they cannot be inspected in the debugger like named functions.

Other Alternatives

There are other ways to filter an array in JavaScript, such as using map() and every(), or using a library like Lodash. However, these alternatives are not being compared in this benchmark.

In summary, this benchmark compares two approaches to filtering arrays: using named functions vs using anonymous arrow functions. The results suggest that the anonymous function approach is faster, but may be less readable for some developers.